Method and system for requesting allocation of bandwith and allocating bandwith in a multi-hop relay environment

ABSTRACT

The present invention relates to a method and a system for requesting the allocation of bandwidth in a multi-hop relay environment. The present invention relates to a method for requesting bandwidth of a relay node in the multi-hop relay environment and a method for allocating bandwidth of a base station. In the invention, single piggybacking and multiple piggybacking based on approval-processing sub-headers are discriminated from single piggybacking and multiple piggybacking based on extensible sub-headers. Therefore, the bandwidth-requests for each CID from the base station are integrated and managed for each relay so that the message transmission and reception load may be reduced and the allocation of bandwidth may be optimized.

TECHNICAL FIELD

The present invention relates in general to a method and system forrequesting the allocation of bandwidth and for allocating bandwidth in amulti-hop relay environment and, more particularly, to a method andsystem for more effectively requesting the bandwidth of mobile stationsamong a base station, a relay station and the mobile stations in themulti-hop relay environment.

BACKGROUND ART

Normally the cellular OFDMA system with a frequency reuse factor 1 suchas IEEE802.16e may confront degradation in transmission ratio due topoor carrier-to-interference and noise ratio (CINR) near cellperipheries and therefore may restrict coverage performance due toservice outage. In order to solve such problems, IEEE 802.16j TG in theIEEE 802.16 Wireless MAN standardization group is pushing ahead with thestandardization of a multi-hop relay (MR) system based on cellularOFDMA. The MR system is composed of a repeater, i.e., a relay station(RS), which supports a radio relay function for connection of a mobilestation (MS), and a base station (BS) which is connected with the MS orRS through a radio link and supports a radio relay function. The MS maydirectly communicate the MR-BS or may be connected with the MR-BSthrough two-hop using a single RS or multi-hop using several RSs. Thissystem simultaneously offers an access zone of the MS and a relay zonebetween the RS and the MR-BS by means of time division of a single radiofrequency channel, thus requiring no additional wired link for a relaylink. Namely, the multi-hop relay system not only can increase yield byimproving CINR performance of the adjoining MS through the RS, but alsomay cover a service outage area or expand cell coverage by installingthe RS in a shaded zone. Accordingly, the multi-hop relay system maydivide the entire cell into a number of small coverage regions throughmulti-hop RSs, and may realize an increase of system capacity throughreuse of the same radio resources by all RSs.

Meanwhile, the MS accesses a specific server or other MS through the BSand then establishes downlink and uplink channels with the BS in orderto use a certain service. Namely, the MS forms a downlink channel withthe BS to receive data from a specific server or other MS, and alsoforms an uplink channel with the BS to upload or transmit data to aspecific server or other MS. Particularly, the MS requests uplinkbandwidth for data transmission to the BS and, for such a request,creates a separate bandwidth request message to be transmitted to theBS.

By the way, if there is any RS between the MS and the BS during abandwidth request process of the MS, the MS sends a bandwidth request tothe RS, and then the RS sends a message corresponding to the bandwidthrequest to the BS. So, if the MS uses several services or if several MSsuse several services, the above messages for bandwidth requests areincreased and hence this may incur an increase of message transmissionload. Therefore, a method and system for a more effective bandwidthrequest are needed.

DISCLOSURE Technical Problem

Accordingly, an aspect of the present invention is to provide a methodand system for requesting the allocation of bandwidth and for allocatingbandwidth in a multi-hop relay environment by allowing each relaystation to integrate and manage bandwidth requests received from atleast one mobile station, thus optimizing data transmission andreception for the bandwidth requests.

Technical Solution

According to one aspect of the present invention, provided is a methodfor requesting the allocation of bandwidth for at least one mobilestation (MS) using several connection identifications (CIDs) in amulti-hop relay environment, the method comprising steps of: at a relaystation (RS), ascertaining the CIDs of the MS that belongs to the RS; atthe RS, detecting bandwidth requesting CID that requires the allocationof bandwidth, among the CIDs; at the RS, creating a field that containsa region for recording CID-related information of the bandwidthrequesting CID and a region for recording bandwidth request informationof the bandwidth requesting CID; and at the RS, adding the created fieldto a media access control (MAC) header that corresponds to CID of apacket transmitted to a base station (BS) among the CIDs.

According to another aspect of the present invention, provided is amethod for allocating bandwidth at a base station (BS) in a multi-hoprelay environment, the method comprising steps of: receiving a fieldthat is added to an MAC header and contains a region for recordingCID-related information of bandwidth requesting CID and a region forrecording bandwidth request information of the bandwidth requesting CID;detecting CID from the CID-related information and also detectingbandwidth information of the detected CID from the bandwidth requestinformation region; and allocating necessary bandwidth to a relaystation (RS) according to the CID and the bandwidth request information.

According to still another aspect of the present invention, provided isa system for requesting the allocation of bandwidth for at least onemobile station (MS) using several connection identifications (CIDs) in amulti-hop relay environment, the system comprising: a relay station (RS)configured to ascertain the CIDs of the MS, to detect bandwidthrequesting CID that requires the allocation of bandwidth among the CIDs,to create a field that contains a region for recording CID-relatedinformation of the bandwidth requesting CID and a region for recordingbandwidth request information of the bandwidth requesting CID, and toadd the created field to a media access control (MAC) header thatcorresponds to CID of a packet transmitted to a base station (BS) amongthe CIDs.

According to yet another aspect of the present invention, provided is asystem for allocating bandwidth in a multi-hop relay environment, thesystem comprising: a relay station (RS) configured to transmit a fieldthat is added to an MAC header and contains a region for recordingCID-related information of bandwidth requesting CID and a region forrecording bandwidth request information of the bandwidth requesting CID;and a base station (BS) configured to detect CID from the CID-relatedinformation, to detect bandwidth information of the detected CID fromthe bandwidth request information region, and to allocate necessarybandwidth to the RS according to the CID and the bandwidth requestinformation.

ADVANTAGEOUS EFFECTS

According to a method and system for requesting the allocation ofbandwidth and for allocating bandwidth in a multi-hop relay environmentproposed by embodiments of this invention, several bandwidth requestsfor several services are integrated and managed at each RS, so that aload for such bandwidth requests can be optimized and also resourcerequests of the MS can be quickly processed thanks to reduced or removedwaiting time for bandwidth requests.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating a configuration of a systemcorresponding to a multi-hop relay environment in accordance with anexemplary embodiment of the present invention.

FIG. 2 is a view illustrating a structure of an MAC signaling header inaccordance with an exemplary embodiment of the present invention.

FIG. 3 is a view illustrating a structure of a generic MAC header inaccordance with an exemplary embodiment of the present invention.

FIG. 4 is a view illustrating a single piggyback scheme based on anRS-CID list in accordance with an exemplary embodiment of the presentinvention.

FIG. 5 is a view illustrating a single piggyback scheme based on aconventional grant management sub-header in accordance with an exemplaryembodiment of the present invention.

FIG. 6 is a view illustrating a multiple piggyback scheme based on anRS-CID list in accordance with an exemplary embodiment of the presentinvention.

FIG. 7 is a view illustrating a multiple piggyback scheme based on abitmap in accordance with an exemplary embodiment of the presentinvention.

FIG. 8 is a view illustrating a multiple piggyback scheme based on aconventional grant management sub-header in accordance with an exemplaryembodiment of the present invention.

FIG. 9 is a view illustrating a structure of an extended sub-header inaccordance with an exemplary embodiment of the present invention.

FIG. 10 is a view illustrating a single piggyback scheme based on anRS-CID list and an extended sub-header in accordance with an exemplaryembodiment of the present invention.

FIG. 11 is a view illustrating a single piggyback scheme using aconventional grant management sub-header and an extended sub-header inaccordance with an exemplary embodiment of the present invention.

FIG. 12 is a view illustrating a multiple piggyback scheme based on anRS-CID list and an extended sub-header in accordance with an exemplaryembodiment of the present invention.

FIG. 13 is a view illustrating a multiple piggyback scheme based on abitmap and extended sub-header in accordance with an exemplaryembodiment of the present invention.

FIG. 14 is a view illustrating a multiple piggyback scheme based onplural conventional grant management sub-headers and an extendedsub-header in accordance with an exemplary embodiment of the presentinvention.

FIGS. 15 and 16 are flow diagrams illustrating a method for requestingthe allocation of bandwidth at a relay station in accordance with anexemplary embodiment of the present invention.

FIG. 17 is a flow diagram illustrating a method for allocating bandwidthat a base station in accordance with an exemplary embodiment of thepresent invention.

MODE FOR INVENTION

Exemplary, non-limiting embodiments of the present invention will now bedescribed more fully with reference to the accompanying drawings. Thisinvention may, however, be embodied in many different forms and shouldnot be construed as limited to the exemplary embodiments set forthherein. Rather, the disclosed embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the invention to those skilled in the art. The principles andfeatures of this invention may be employed in varied and numerousembodiments without departing from the scope of the invention.

Furthermore, well known or widely used techniques, elements, structures,and processes may not be described or illustrated in detail to avoidobscuring the essence of the present invention. Although the drawingsrepresent exemplary embodiments of the invention, the drawings are notnecessarily to scale and certain features may be exaggerated or omittedin order to better illustrate and explain the present invention.

A mobile station (MS) which tries to use a certain service should have aspecific identifier regarding that service. Connection identification(CID), formed for each service by the MS with a relay station (RS) or abase station (BS), may be used as such an identifier for identifying aparticular service. Hereinafter, CID may refer to an identifier fordifferentiating each service from the others. Also, MS-CID may refer toCID corresponding to each service possessed by the MS, and RS-CID mayrefer to CID mapped to MS-CID by the RS according to a given rule.Therefore, the value of CID may be varied for each MS and RS. However,the MS that substantially possesses CID, a service corresponding to CID,etc. is unvarying.

Additionally, bandwidth information set forth herein may refer toinformation about the amount of bandwidth, which may be informationabout the bandwidth amount itself or be index information correspondingto the bandwidth amount.

Meanwhile, for each bandwidth request CID that requests the allocationof bandwidth, the RS writes a region for CID-related information and aregion for bandwidth request information. The CID-related informationmay include CID information about the bandwidth request CID, sequenceinformation of such CIDs arranged in a list according to a given rule,and information about bitmap created being based on the list of suchCIDs.

FIG. 1 is a schematic view illustrating a configuration of a systemcorresponding to a multi-hop relay environment in accordance with anexemplary embodiment of the present invention.

Referring to FIG. 1, the multi-hop relay environment may include the BS30, the RS 20 and the MS 10. Although the multi-hop relay environment tobe discussed herein employs a single RS 20, this is exemplary only andnot to be considered as a limitation of the present invention. In analternative embodiment, a plurality of RSs 20 may be connected to the BS30, and each RS 20 may communicate with a plurality of MSs 10.

In a communication system of the multi-hop relay environment having theabove configuration, at least one BS 10 requests bandwidth to the BS 30through the RS 20, based on CID corresponding to each service currentlyused in the MS 10. At this time, if the MS 10 uses several services andthereby has several MS-CIDs, or if several MSs 10 use their own serviceand thereby request bandwidth depending on their own MS-CID, the RS 20simultaneously classifies MS-CIDs of the MSs 10 and then requestsbandwidth to the BS 30. Therefore, the RS 20 not only can prevent anincrease of unnecessary overhead during a message transmission andreception for bandwidth requests of the MSs 10, but also can supportwriting of a bandwidth allocation request message optimized according toa system in a bandwidth request. Now, the respective elements aredescribed in detail.

The BS 30 establishes a communication channel with the MS 10 through theRS 20. This communication channel may include a downlink (DL) channelfor data transmission from the BS 30 to the RS 20 or from the BS 30 tothe MS 10 via the RS 20, and an uplink (UL) channel for datatransmission from the MS 10 or the RS 20 to the BS 30. The BS 30periodically checks whether the RS 20 will request bandwidth or, whenreceiving a message corresponding to a bandwidth request from the RS 20,sends an UL map for bandwidth allocation to the RS 20. The UL map refersto a specific map about resources of the entire UL. This UL map mayrepresent bandwidth that is currently available for the RS 20 andbandwidth that has been already allocated to other RS 20 or other MS 10.

Additionally, the BS 30 transmits and receives necessary information toand from the RS 20 in the initialization process. Through this process,the BS 30 can know which RS 20 exists in its communication area and alsocan know which RS 20 uses which RS-CID. Furthermore, since the BS 30receives from the RS 20 information about the entry of the MS 10 intothe area of the RS 20, the BS 30 can know which MS 10 exists in which RS20. Therefore, the BS 30 can create and manage, for each RS, a list ofRS-CID corresponding to MS-CID of the MS.

The MS 10 establishes a communication channel with the BS 30 through theRS 20 and then may request the allocation of bandwidth to the BS 30 viathe RS 20 in order to perform a particular service, e.g., datatransmission toward the BS 30. For instance, for uploading ortransmission of a photo, a document or a mail through the UL, the MS 10may request the allocation of bandwidth to the BS 30 via the RS 20 and,when bandwidth is allocated, may perform a selected service. Meanwhile,depending on the circumstances, a single MS 10 may use several services,and two or more MSs 10 may use several services. Here, in order todistinguish each service from the others and also to maintain acurrently used service, the MS 10 creates various messages (e.g., amessage for maintaining a current service, a message for requestingbandwidth allocation, etc.) based on CID (i.e., MS-CID) predefined andcorresponding to each service, and then sends them to the RS 20. Also, asingle MS 10 may use several services and thereby may employ severalMS-CIDs. Alternatively, several MSs 10 may employ several MS-CIDs.Therefore, when requesting the allocation of bandwidth for use of aparticular service, each MS 10 writes a bandwidth request header havingeach CID, as shown in FIG. 2, and then sends it to the RS 20. Referringto FIG. 2, the bandwidth request header may include a header type (HT)filed 201, an encoding (EC) field 203, a type filed 205, bandwidthrequest (BR MSB (11), BR LSB (8)) fields 207 and 209, CID fields 211 and213, and a header check sequence (HCS) field 215.

The RS 20 establishes communication channels with the MS 10 and with BS30 and then transmits data from the MS 10 to the BS 30 and vice versa.Specifically, the MS 10 uses MS-CID for a service initialization andservice maintenance during the use of a particular service. If theallocation of bandwidth is required for additional data transmission,the MS 10 creates an MS-CID message containing request information aboutbandwidth allocation for each MS-CID and then sends each MS-CID messageto the RS 20.

At this time, if there is any UL packet transmitted to the BS throughthe RS, the RS 20 may write information about RS-CID mapped to MS-CID ofa bandwidth request as well as bandwidth request information in apiggyback request header that is a type of grant management sub-headerconnected to a generic MAC (media access control) header, and then maysend it to the BS.

Alternatively, the RS 20 may detect CID information and requiredbandwidth allocation information from the first one of MS-CID messagesrequesting the allocation of bandwidth, and then creates an RS-CIDmessage corresponding to the bandwidth request MS-CID by writing thedetected information and RS-CID mapped to the above MS-CID in a genericMAC header. Additionally, for the second MS-CID message requesting theallocation of bandwidth, the RS 20 determines RS-CID through itsmapping, writes the determined RS-CID and required bandwidth allocationrequest information in a sub-header connected to the generic MAC header,and then transmits this message to the BS 30.

Thereafter, the RS 20 receives the UL map corresponding to the aboveRS-CID message from the BS 30 and ascertains grantable bandwidth in theUL map. Then, based on this, the RS 20 allocates bandwidth requested bythe MS 10 to the MS 10 for each MS-CID.

In other words, the RS 20 may perform a bandwidth allocation requestprocess by creating RS-CID corresponding to MS-CID of the MS 10, addinga grant management sub-header to a generic MAC header based on aspecific MS-CID, and then sending it to the BS 30. In addition, the RS20 may perform such a process by adding an extended sub-header to aspecific generic MAC header transmitted to the BS 30. Also, in case ofhaving to process the bandwidth allocation requests many times, the RS20 may add several grant management sub-headers to the generic MACheader.

Now, a generic MAC header used by the RS 20 is described in detail withreference to FIG. 3.

FIG. 3 is a view illustrating a structure of a generic MAC header inaccordance with an exemplary embodiment of the present invention.

Referring to FIG. 3, the generic MAC header includes a header type (HT)field 301, an encoding (EC) field 302, a type field 303, an extendedsub-header field (ESF) 304 indicating whether an extended sub-header ispresent or not, a CRC indicator (CI) field 305 indicating a cyclicredundancy check (CRC) error, an encryption key sequence (EKS) field 307having information about a key used for payload encryption, an extendedpiggyback request (e-PBR) field 309 which is newly defined in thepresent invention, length (LEN) fields 311 and 313, CID fields 315 and317, and a header check sequence (HCS) field 319. Here, some indicatorsdefining various types may be entered in the type field 303, which mayespecially include a least significant bit (LSB) 321 used for adefinition of a message for a bandwidth allocation request of theinvention.

Meanwhile, a piggyback request scheme is to set up the LSB of the typefield 303 in the generic MAC header in order for the grant managementsub-header to be added. Namely, the piggyback request scheme is a way torequest the allocation of bandwidth by setting the type filed LSB 321 to‘1’, adding the 2-byte grant management sub-header, which recordsinformation about bandwidth allocation request necessary forcorresponding CID, to the generic MAC header, and then performingtransmission. Here, the grant management sub-header records informationabout how many bytes of bandwidth are further required for thecorresponding CID to which certain bandwidth has been already allocated.This information recorded in the grant management sub-header may bevaried according to service classes of the CID. The grant managementsub-header format may be represented as Table 1 given below.

TABLE 1 Syntax Size(bits) Notes Grant management D D subheader( ){If(scheduled service D D type == UGS){ SI 1 D PM 1 D FU 1 D FL 4 DReserved 9 Shall be set to zero }else if(scheduled D D service type =extended rtps)} Extended Piggyback 11 D Request FU 1 D FL 4 D }else{ D DD PiggyBack Request 16 D } D D } D D

Table 1 exemplarily shows the grant management sub-header format of theunsolicited guaranteed service (UGS) and the extended real time pollingservice (rtPS). However, the contents of the grant management sub-headermay be varied according to service classes. In addition to theabove-mentioned UGS and the extended rtPS, such scheduling serviceclasses may be an rtPS, a non real time polling service (nrtPS), and abest effort (BE) service.

Table 2 shows fields of the grant management sub-header.

TABLE 2 Length Name (bits) Description SI 1 Slip indicator( ) = NoAction1 = Used by the MS to indicate a Slip of uplink grants relative tothe uplink queue depth PM 1 Poll-Me0 = No Action1 = used by the MS torequest a bandwidth poll FU 1 Frame Latency indication0 = Frame latencyfield disabled for this grant1 = Frame latency field enabled for thisgrant FL 4 Frame Latency. The number of frames previous to the currentone in which the transmitted data was available. When the latency isgreater than 15 then the FL field shall be set to 15. Extended 11Extended PiggyBack Request. The number of PBR bytes of uplink bandwidthrequested by the MS. The bandwidth request is for the CID. The requestshall not include any PHY overhead. The request shall be incremental. Incase of the extended rtPS, if the MSB is 1, the BS changes its pollingsize into the size specified in the LSBs of this field. PiggyBack 16PiggyBack Request. The number of bytes uplink Request bandwidthrequested by the MS.

In the above-discussed generic MAC header structure, a bandwidthallocation request method proposed by this invention includes a methodin which the RS 20 performs a single piggyback scheme for other CID ofthe MS or CID of other MS corresponding to CID of the generic MAC headerand then requests the allocation of bandwidth, and another method inwhich the RS 20 performs a multiple piggyback scheme for several CIDs ofthe MS corresponding to CID of the generic MAC header and then requeststhe allocation of bandwidth. Such methods may be discriminated by acombination of the type field LSB 321 and the e-PBR 309 bit in thegeneric MAC header structure. This will be described in more detail withreference to Table 3.

TABLE 3 e-PBR LSB field bit Operation 0 0 No piggyback 1 0 RS-CID ofgeneric MAC header performs BR with piggyback 1 1 Single piggyback thatallows piggyback of other RS-CID in RS to which RS-CID of generic MACheader belongs 0 1 Multiple piggyback

As shown in Table 3, the bandwidth allocation request method offered bythe RS 20 may be classified into four schemes according to a combinationof the type field LSB and the e-PBR. Specifically, in case of performingno piggyback, the RS 20 sets each of the LSB bit and the e-PBR bit ofthe generic MAC header to “0”. Additionally, in case where CID thatneeds the allocation of bandwidth would like to request the allocationof bandwidth by performing a piggyback based on a single CID containedin the generic MAC header, the RS 20 sets the LSB bit to “1” and thee-PBR bit to “0”. Particularly, in case where CID that needs theallocation of bandwidth is other than the MS corresponding to CIDcontained in the generic MAC header, the RS 20 of this inventionperforms a single piggyback by setting the LSB bit to “1” and the e-PBRbit to “1”. Finally, in case of a multiple piggyback that requests theallocation of bandwidth for several CIDs different from CID contained inthe generic MAC header, the RS 20 sets the LSB bit to “0” and the e-PBRbit to “1”.

Hereinafter, in a method for requesting the allocation of bandwidthaccording to embodiments of this invention, a prearranged region of thegeneric MAC header is defined as the e-PBR for each of a singlepiggyback scheme and a multiple piggyback scheme, In addition, a way ofadding a sub-header according to the definitions of the LSB field andthe e-PBR field, and a way of using an extended sub-header is describedin detail with reference to the drawings.

First, in a single piggyback scheme and a multiple piggyback scheme,bandwidth allocation request methods based on a generic MAC header and asub-header connected thereto are described with reference to FIGS. 4 to8.

FIG. 4 is a view illustrating a single piggyback scheme based on anRS-CID list in accordance with an exemplary embodiment of the presentinvention. Namely, FIG. 4 shows a process of a bandwidth allocationrequest using the RS-CID list in the single piggyback scheme using thegeneric MAC header and the sub-header.

Since the BS allocates CID to each MS, the BS knows the MS that existsin its coverage and also knows CID of each MS. When the MS is connectedto a certain RS, the BS offers such information about the MS to the RS.Therefore, the RS can know all CID information about the MS connectedthereto.

Referring to FIG. 4, in this single piggyback scheme, the first MS (MS100) has three CIDs, namely MS-CID #100, MS-CID #105 and MS-CID #205,and the second MS (MS 200) has four CIDs, namely MS-CID #252, MS-CID#301, MS-CID #302 and MS-CID #367.

The RS 20 performs a mapping between each MS-CID of the first MS (MS100) and its own RS-CID and between each MS-CID of the second MS (MS200) and its own RS-CID. For instance, the RS 20 may perform a mappingto connect RS-CID #1, RS-CID #2 and RS-CID #3 to MS-CIDs of the first MS(MS 100), respectively, and also to connect RS-CID #4, RS-CID #5, RS-CID#6 and RS-CID #7 to MS-CIDs of the second MS (MS 200), respectively.This mapping process depends on a predefined CID matching form, and thisinvention is not limited to the above CID numbers. After an RS-CIDmapping is completed, the RS 20 arranges RS-CIDs according to a givenrule and then makes a list of the arranged RS-CIDs.

Herein, let's suppose that RS-CID #2 corresponding to MS-CID #105transmitted from the first MS (MS 100) is contained in a messagetransmitted to the BS 30, and that MS-CID #302 transmitted from thesecond MS (MS 200) is a bandwidth requesting CID. In this case, the RS20 makes a generic MAC header 40 containing RS-CID #2 and also sets eachof the LSB field and the e-PBR field of the generic MAC header 40 to“1”. Then the RS 20 writes PBR information related to RS-CID #6 (i.e.,RS-CID information of RS-CID #6 and bandwidth allocation requestinformation needed by RS-CID) in the 2-byte grant management sub-header41 added to the generic MAC header 40. For this, the RS 20 divides thegrant management sub-header 41 into two regions, namely an RS-CID toPBR(n) region 43 and a PBR(16-n) region 45. Then the RS 20 may writebandwidth requesting CID information or any information corresponding tothe bandwidth requesting CID information in the RS-CID to PBR(n) region43 and also may write required bandwidth allocation request informationin the PBR(16-n) region 45. At this time, since 2 bytes are allocated tothe grant management sub-header 41, if CID information of RS-CID #6exceeds certain bits (e.g., 5 bits), it is desirable to use a schemeshown in FIG. 5 instead of using “reduced RS-CID” based on the RS-CIDlist. Since “reduced RS-CID” is created by being based on the RS-CIDlist, all RS-CIDs based on MS-CIDs that belong to the first MS (MS 100)and the second MS (MS 200) are arranged by the RS as discussed above. Atthis time, the RS can know the location of each RS-CID in the RS-CIDlist. Therefore, the RS can 20 know that RS-CID #6 is located at thesixth position in the RS-CID list and may use “6” as reduced RS-CIDinformation. When the RS 20 transmits to the BS 30 a message containingthe grant management sub-header 41 added to the generic MAC header 40 onthe basis of such reduced RS-CID information, the BS 30 can ascertainwhich RS sends the RS-CID list, by checking RS-CID of the generic MACheader 40. Also, by checking the reduced RS-CID information and thecontents recorded in the grant management sub-header 41, the BS 30 canknow how many bytes of bandwidth are required for each MS-CID.

The size n of the “RS-CID to PBR” field may be calculated throughEquation 1.

n=min(5·m)  [Equation 1]

Here, if k is the number of CIDs arranged in the RS-CID list of the RSto which CID of the generic MAC header belongs, m is selected to satisfy2̂m≧k. For instance, if the total number of CIDs in the RS-CID list is12, it is possible that k=12, m=4 and n=4 for 2̂4≧12. If the minimumrequired size of the PBR field is 11 bits, the field size n of the“RS-CID to PBR” may be allowed up to 5 bits.

Meanwhile, if the number of CIDs in the RS-CID list is greater than acertain number expressible by the size of the RS-CID to PBR field, theRS 20 cannot perform a proper distinction of CIDs. For instance, if thesize of the RS-CID to PBR field is “5”, the RS 20 can distinguish up tototal 32 CIDs but cannot distinguish CIDs more than 32. Therefore, theRS 20 supports a proper bandwidth allocation request using a datastructure as shown in FIG. 5.

FIG. 5 is a view illustrating a single piggyback scheme based on aconventional grant management sub-header in accordance with an exemplaryembodiment of the present invention. Namely, FIG. 5 shows a way ofadding a field for a bandwidth requesting RS-CID to the generic MACheader and also adding a piggyback sub-header containing bandwidthrequest information of the RS-CID thereto, in case where it is difficultto use reduced RS-CID when a request for bandwidth is received fromother CID of the RS to which CID of the generic MAC header belongs. Inthis case, it is possible to use a conventional grant managementsub-header as a piggyback header.

Referring to FIG. 5, the RS 20 establishes RS-CIDs mapped to MS-CIDs ofthe first and second MSs (MS 100 and MS 200) and, based thereon, maymake an RS-CID list. If one (e.g., RS-CID #6) of CIDs contained in theRS-CID list has contents requesting the allocation of bandwidth, the RS20 transmits a message, as shown, to the BS. In this case, the RS 20uses a conventional grant management sub-header 53, discussed earlier inTable 1, for a bandwidth allocation request for RS-CID #6. Here, theconventional grant management sub-header 53 contains only “PBR for theRS-CID” information that is bandwidth allocation request informationrequired for RS-CID #6. Therefore, a 2-byte sub-header 51 that contains“RS-CID to PBR” information having RS-CID #6 information is transmittedtogether with the conventional grant management sub-header 53.

Namely, the RS 20 adds the sub-header 51 as well as the conventionalgrant management sub-header 53 to the generic MAC header 50 containingRS-CID #2 information and then transmits it to the BS 30.

Meanwhile, the BS 30 that receives the aforesaid message from the RS 20checks the LSB bit and the e-PBR bit of the generic MAC header 50. Ifeach bit is set to “1”, the BS 30 can know that the received message isfor a single piggyback. Then the BS 30 detects CID informationcorresponding to bandwidth requiring RS-CID #6 from the sub-header 51,detects bandwidth required for RS-CID #6 through the conventional grantmanagement sub-header 53, and allocates the detected bandwidth to the RS20.

Here, the RS 20 may not need to make a separate RS-CID list when writingbandwidth allocation request information of the RS-CID by using theconventional grant management sub-header 53 and also writing CIDinformation of RS-CID #6 by using the sub-header 51. Additionally, eventhough using MS-CID itself instead of using RS-CID to which MS-CID ismapped, the RS 20 may transmit a message for requesting the samebandwidth.

As discussed, in a single piggyback scheme of this invention, the methodfor requesting the allocation of bandwidth can minimize CID-relatedinformation for a bandwidth allocation request by sending it through thegeneric MAC header transmitted to the BS 30, thus minimizing a loadcaused by message transmission for a bandwidth allocation request.Additionally, the bandwidth allocation request method according to asingle piggyback scheme of this invention can be performed regardless ofpolling cycle of the BS 30 for a check of a bandwidth allocationrequest, thus minimizing an unnecessary time delay.

Next, in a multiple piggyback scheme, a bandwidth allocation requestmethod is described.

FIG. 6 is a view illustrating a multiple piggyback scheme based on anRS-CID list in accordance with an exemplary embodiment of the presentinvention. Namely, FIG. 6 shows a process of arranging bandwidthrequesting RS-CIDs in order according to the RS-CID list and then makinga message in the multiple piggyback scheme.

Referring to FIG. 6, the RS 20 creates an RS-CID list by arrangingMS-CIDs of the first and second MSs (MS 100 and MS 200) according to agiven rule. Namely, the RS 20 performs a mapping so that MS-CID #100,MS-CID #105 and MS-CID #205 of the first MS (MS 100) and MS-CID #252,MS-CID #301, MS-CID #302 and MS-CID #367 of the second MS (MS 200) maybe mapped to its own prearranged RS-CIDs according to a given rule.Specifically, MS-CID #100 is mapped to RS-CID #1, MS-CID #105 is mappedto RS-CID #2, and MS-CID #205 is mapped to RS-CID #3. Additionally,MS-CID #252 is mapped to RS-CID #4, MS-CID #301 is mapped to RS-CID #5,MS-CID #302 is mapped to RS-CID #6, and MS-CID #367 is mapped to RS-CID#7. This invention is not limited to the above CID mapping numbers,which may be varied according to a given rule.

Herein, let's suppose that MS-CID #205 of the first MS (MS 100) andMS-CIDs #252 and #302 of the second MS (MS 200) are bandwidth requestingMS-CIDs.

In the above mapping process, the RS 20 checks whether there is anyMS-CID having contents for a bandwidth allocation request among MS-CIDsof the first and second MSs (MS 100 and MS 200). At this time, in orderto request the allocation of bandwidth to the RS, the first and secondMSs (MS 100 and MS 200) may perform in general a conventional bandwidthrequest process. Then the RS 20 creates a bandwidth allocation requestmessage, as shown, based on the RS-CID list that contains RS-CID #3,RS-CID #4 and RS-CID #6 corresponding to the respective bandwidthrequesting MS-CIDs. Here, by setting the LSB bit of the message to “0”and the e-PBR bit to “1”, the RS 20 may indicate that the message is torequest the allocation of bandwidth for several CIDs. After writing CIDinformation of RS-CID #3 in the CID field of the generic MAC header 60,the RS 20 writes sub-headers added to the generic MAC header 60. Thesesub-headers may include the first sub-header 62 for recording PBRcorresponding to bandwidth allocation request information of RS-CID #3,the second sub-header 64 for recording PBR corresponding to bandwidthallocation request information of RS-CID #4, and the third sub-header 66for recording PBR corresponding to bandwidth allocation requestinformation of RS-CID #6.

The first sub-header 62 has a “The number of PBR(n)” region 61 and a“PBR for CID in generic MAC header(16-n)” region 63. The “The number ofPBR(n)” region 61 indicates the total number of PBRs requesting theallocation of bandwidth. Here, the size n may be calculated throughEquation 1 described earlier. The “PBR for CID in generic MACheader(16-n)” region 63 records bandwidth allocation request information(e.g., bytes of bandwidth) required by RS-CID #3.

Each of the second and third sub-headers 64 and 66 has an “RS-CID toPBR(n)” region 65 and a “PBR(16-n)” region 67. The “RS-CID to PBR(n)”region 65 of the second sub-header 64 may record information (i.e., “4”)about the location of RS-CID #4 in the RS-CID list, and the “RS-CID toPBR(n)” region of the third sub-header 66 may record information (i.e.,“6”) about the location of RS-CID #6 in the RS-CID list. Additionally,the “PBR(16-n)” region 67 of the second sub-header 64 records bandwidthallocation request information required for RS-CID #4, and the“PBR(16-n)” region of the third sub-header 66 records bandwidthallocation request information required for RS-CID #6.

Then the RS 20 transmits to the BS 30 the above message, namely,including the generic MAC header 60 containing CID of RS-CID #3, thefirst sub-header 62 containing the total number of sub-headers andbandwidth allocation request information about RS-CID #3, the secondsub-header 64 containing CID information and bandwidth allocationrequest information about RS-CID #4, and the third sub-header 66containing CID information and bandwidth allocation request informationabout RS-CID #6.

Then the BS 30 receives the above message and checks the LSB bit and thee-PBR bit of the generic MAC header 60. If both bits are set to “0” and“1”, respectively, the BS 30 recognizes the received message to be amultiple piggyback message. Additionally, the BS 30 can know how manyCIDs request the allocation of bandwidth by checking the firstsub-header 62, and also can know the total amount of bandwidthallocation by checking the respective sub-headers. Then the BS 30 offersa corresponding bandwidth allocation map (e.g., the UL map) to the RS20.

When receiving the UL map from the BS 30, the RS 20 checks availablebandwidth allocation regions from the UL map, creates an UL-MAP basedthereon, and sends it to the first and second MSs (MS 100 and MS 200).Then each of the first and second MSs (MS 100 and MS 200) recognizesbandwidth allocation for corresponding MS-CID from the RS 20 and mayperform data transmission through the allocated bandwidth.

As discussed, in case of having several MS-CIDs that request theallocation of bandwidth, the RS 20 creates the RS-CID list based on allMS-CIDs within its coverage, and also fixes the order of bandwidthrequesting RS-CIDs. Then, for each CID, the RS 20 adds a sub-header fora bandwidth allocation request to the generic MAC header for specificRS-CID to be transmitted to the BS 30 while using an index value of eachCID as the sequence number of each CID. Therefore, the RS 20 canminimize the size of a bandwidth allocation request message through aprocess of adding a 2-byte sub-header for each bandwidth requesting CID,thus allowing an integrated management of several bandwidth requestingCIDs.

Meanwhile, the RS 20 may support a quick distinction of bandwidthrequesting RS-CIDs by mapping all CIDs to certain bitmaps. For this, theRS 20 may make a message as shown in FIG. 7.

FIG. 7 is a view illustrating a multiple piggyback scheme based on abitmap in accordance with an exemplary embodiment of the presentinvention. Namely, FIG. 7 shows a process of making a bandwidthallocation request message by mapping all RS-CIDs to bitmaps in themultiple piggyback scheme.

Referring to FIG. 7, the RS 20 creates an RS-CID list by arrangingMS-CIDs according to a given rule. Namely, the RS 20 performs a mappingbetween MS-CID and RS-CID. Specifically, MS-CID #100 is mapped to RS-CID#1, MS-CID #105 is mapped to RS-CID #2, and MS-CID #205 is mapped toRS-CID #3. Additionally, MS-CID #252 is mapped to RS-CID #4, MS-CID #301is mapped to RS-CID #5, MS-CID #302 is mapped to RS-CID #6, and MS-CID#367 is mapped to RS-CID #7. This invention is not limited to the aboveCID mapping numbers, which may be varied according to a given rule.

Herein, let's suppose that MS-CID #205 of the first MS (MS 100) andMS-CIDs #252 and #302 of the second MS (MS 200) are bandwidth requestingMS-CIDs.

In order to request the allocation of bandwidth, the first and secondMSs (MS 100 and MS 200) may use a conventional method for requestingbandwidth to the BS.

Next, the RS 20 allocates “0” to MS-CID that does not request bandwidthallocation, and allocates “1” to MS-CID that requests bandwidthallocation. Consequently, RS-CID #3, RS-CID #4 and RS-CID #6,corresponding to each MS-CID that requests the allocation of bandwidth,are assigned “1” and the other RS-CIDs are assigned “0”. Therefore, incase of this example, the RS 20 may create a bitmap “0011010”corresponding to the entire RS-CID list.

After the above bitmap creation process is completed, the RS 20 writesthe generic MAC header 70 based on CID contained in specific RS-CID(e.g. RS-CID #2) to be transmitted to the BS 30 and also sets the LSBbit and the e-PBR bit of the generic MAC header 70 to “0” and “1”,respectively. Then the RS 20 writes a sub-header 71 that is added to thegeneric MAC header 70 and also records the aforesaid bitmap information“RS-CID BR bitmap”. Additionally, the RS 20 writes conventional grantmanagement sub-headers 72, 74 and 76 that are added to the abovesub-header 71 and record bandwidth allocation request information foreach CID, and then performs a piggyback request.

Thereafter, the RS 20 transmits to the BS 30 a message that contains thegeneric MAC header 70 corresponding to RS-CID #2, the sub-header 71adjoining the generic MAC header 70 and containing RS-CID BR bitmap, andconventional grant management sub-headers 72, 74 and 76 adjoining thesub-header 71 and containing bandwidth allocation request informationdetected from RS-CID #3, RS-CID #4 and RS-CID #6. Here, the RS 20 mayfix RS-CID BR bitmap to a specific bit or may apply flexibly it. In casewhere the RS 20 fixes the size of RS-CID BR bitmap, for example, to 2bytes, the total number of RS-CIDs processed by the RS 20 does notexceed 16. Also, in case of 2-byte bitmap, the RS 20 may assign theaforesaid bitmap “0011010” to former 7 bits and assign “0” to the otherbits. Therefore, the entire bitmap may become “0011010000000000”.

The BS 30 receives the message from the RS 20 and checks the LSB bit andthe e-PBR bit of the generic MAC header 70. If both bits are set to “0”and “1”, respectively, the BS 30 recognizes the received message to befor a multiple piggyback. Additionally, the BS 30 can know which RS-CIDrequires bandwidth allocation by checking bitmap, and also can know theamount of bandwidth actually required by the RS-CID by checkingconventional sub-headers 72, 74 and 76 added to the sub-header 71. Inthis process, the BS 30 makes an UL map for the allocation of requiredbandwidth by matching the order of conventional sub-headers and CID ofRS-CID requiring bandwidth allocation, and then sends the UL map to theRS 20.

When receiving the UL map from the BS 30, the RS 20 controls properbandwidth allocation, based on the received UL map, for MS-CID of eachMS that requires bandwidth allocation.

As discussed, in case where the total number of CIDs is expressible witha certain bitmap, the bandwidth allocation request method using bitmapamong a multiple piggyback scheme may quickly make and recognize anindex for distinction of CIDs requiring bandwidth allocation, and maywrite bandwidth allocation request information in a conventional grantmanagement sub-header to thereby support the allocation of requiredbandwidth.

Meanwhile, if the total number of CIDs exceeds a specific bit numberallocated for distinction of CID (e.g., the number expressible by 5bits), for example, if forty CIDs should be processed, or if anexcessive bit number should be allocated when the aforesaid bitmap isused, the RS 20 may make a message as shown in FIG. 8.

FIG. 8 is a view illustrating a multiple piggyback scheme based on aconventional grant management sub-header in accordance with an exemplaryembodiment of the present invention. Namely, FIG. 8 shows a process ofmaking a bandwidth allocation request message regardless of the totalnumber of RS-CIDs or list in the multiple piggyback scheme.

Referring to FIG. 8, the RS 20 performs a mapping between MS-CID andRS-CID. Specifically, MS-CID #100 is mapped to RS-CID #1, MS-CID #105 ismapped to RS-CID #2, and MS-CID #205 is mapped to RS-CID #3.Additionally, MS-CID #252 is mapped to RS-CID #4, MS-CID #301 is mappedto RS-CID #5, MS-CID #302 is mapped to RS-CID #6, and MS-CID #367 ismapped to RS-CID #7. This invention is not limited to the above CIDmapping numbers, which may be varied according to a given rule.

Herein, let's suppose that MS-CID #205 of the first MS (MS 100) andMS-CIDs #252 and #302 of the second MS (MS 200) are bandwidth requestingMS-CIDs.

In order to request the allocation of bandwidth, the first and secondMSs (MS 100 and MS 200) may use a conventional method for requestingbandwidth to the BS. Then the RS 20 writes the generic MAC header 80based on CID contained in bandwidth requesting RS-CID #3 and alsorecords bandwidth allocation request information in the first sub-header83 added to the generic MAC header 80. Here, the first sub-header 83 hasa “The number of PBR(n)” region 81 and a “PBR for CID in generic MACheader(16-n)” region 82. The “The number of PBR(n)” region 81 indicatesthe total number of PBRs requesting the allocation of bandwidth. Here,the size n may be calculated through Equation 1 described earlier. The“PBR for CID in generic MAC header(16-n)” region 82 records bandwidthallocation request information (e.g., bytes of bandwidth) required byRS-CID #3.

Meanwhile, the RS 20 records bandwidth allocation request informationcorresponding to RS-CID #4 and RS-CID #6 in the second sub-header (i.e.,a conventional grant management sub-header) 85 and the third sub-header87, respectively. In this example, since the second and thirdsub-headers 85 and 87 record only required bandwidth allocation requestinformation, other sub-headers 84 and 86 with distinguishable CID areadded to the existing sub-headers 85 and 87, respectively. Consequently,by setting the LSB bit and the e-PBR bit of the generic MAC header 70 to“0” and “1”, respectively, the RS 20 indicates that this message is fora multiple piggyback. Then the RS 20 writes the first sub-header 83added to the generic MAC header 80, while recording the aforesaid “Thenumber of PBR(n)” region 81 and the aforesaid “PBR for CID in genericMAC header(16-n)” region 82.

Additionally, the RS 20 adds a sub-header 84 to the first sub-header 83to record other bandwidth requiring CID (i.e., RS-CID #4) and thenrecords bandwidth allocation request information required by RS-CID #4in the second sub-header 85 adjacent to the sub-header 84. Similarly,the RS 20 adds another sub-header 86 to the second sub-header 85 torecord CID of RS-CID #6 and then records bandwidth allocation requestinformation required by RS-CID #6 in the third sub-header 87 adjacent tothe sub-header 86. Then the RS 20 transmits this message to the BS 30.

The BS 30 receives the message from the RS 20 and checks the LSB bit andthe e-PBR bit of the generic MAC header 80. If both bits are set to “0”and “1”, respectively, the BS 30 recognizes the received message to befor a multiple piggyback. Additionally, the BS 30 ascertains the totalnumber of PBRs by checking the sub-header 83 added to the generic MACheader 80. In this process, by checking the aforesaid “PBR for CID ingeneric MAC header(16-n)” region 82, the BS 30 can obtain bandwidthallocation request information required by CID contained in the genericMAC header 80. Thereafter, the BS 30 checks the other sub-headers 84,85, 86 and 87, thereby obtains total CID information and total bandwidthallocation request information required by the RS 20, and then transmitsthe UL map for the allocation of required bandwidth to the RS 20.

When receiving the UL map from the BS 30, the RS 20 creates an UL-MAPfor allocating bandwidth corresponding to CIDs of the first and secondMSs (MS 100 and MS 200) and then sends it to each MS. The MS receivesthe UL-MAP from the RS 20 and, based on allocated bandwidth, transmitsdata to the BS 30.

As discussed, in several types of multiple piggyback scheme, the RS 20not only writes a generic MAC header and a sub-header corresponding tobandwidth requiring RS-CID, but also includes a sub-header recording CIDinformation and a conventional grant management sub-header containingbandwidth allocation request information. Therefore, the RS 20 does notneed any separate RS-CID list and can make a bandwidth allocationrequest message by using MS-CID received from the MS as it is.

Described hereinbefore are methods for performing a single piggyback ora multiple piggyback by using a generic MAC header and an adjoininggrant management sub-header among methods for requesting the allocationof bandwidth according to embodiments of this invention. Now, amongbandwidth allocation request methods according to embodiments of thisinvention, methods for using a generic MAC header and an extendedsub-header that may be defined in the generic MAC header are discussed.

In order to use an extended sub-header, a bandwidth allocation requestmethod of this invention should set an extended sub-header field (ESF)of the generic MAC header to “1”. The ESF bit indicates whether anextended sub-header is present or not. Therefore, the RS 20 which plansto use an extended sub-header sets the ESF bit to “1” and adds theextended sub-header to the generic MAC header to be sent to the BS.

Before a discussion of a method using the extended sub-header, astructure of the extended sub-header is described with reference to FIG.9.

FIG. 9 is a view illustrating a structure of an extended sub-header inaccordance with an exemplary embodiment of the present invention.

Referring to FIG. 9, the extended sub-header includes an extendedsub-header group length field 1401, a reserve field 1403, an extendedsub-header type 1 field 1405, an extended sub-header body 1 field 1407,etc. Here, the type of extended sub-header may be defined up to 128,depending on a value of the extended sub-header type 1 field 1405.According as a new type of extended sub-header is defined, acorresponding extended sub-header body is also defined.

Namely, when extended sub-headers are added to the generic MAC header tobe transmitted, the entire length of extended sub-headers is firstindicated and then any other necessary extended sub-headers are added inorder by referring to Tables 4 and 5 given below. These extendedsub-headers may be distinguished depending on a value of each extendedsub-header type field 1405 of the UL and the DL. Table 4 shows the typesof extended sub-header distinguished according to a value of theextended sub-header type field 1405 in the UL.

TABLE 4 Extended Extended sub- sub-header header body size type Name(byte) 0 SDU_SN extended sub-header 1 1 DL sleep control extended sub- 3header 2 Feedback request extended sub- 3 header 3 SN request extendedsub-header 1 4 PDU SN (short) extended sub- 1 header 5 PDU SN (long)extended sub- 2 header 6-127 Reserved —

Table 5 shows the types of extended sub-header distinguished accordingto a value of the extended sub-header type field 1405 in the DL.

TABLE 5 Extended Extended sub- sub-header header body size type Name(byte) 0 MIMO mode feedback extended 1 sub-header 1 UL Tx power reportextended sub- 1 header 2 Mini-feedback extended sub- 2 header 3 PDU SN(short) extended sub- 1 header 4 PDU SN (long) extended sub- 2 header5-127 Reserved —

Therefore, this invention proposes a method for requesting theallocation of bandwidth through a single or multiple piggyback scheme byusing a reserved region in case where a value of the extended sub-headertype field 1405 in the UL is 6 to 127 and in case where a value of theextended sub-header type field 1405 in the DL is 5 to 127.

Hereinafter, a value “A” of the extended sub-header type field 1405 isdefined as case where the RS requests the allocation of bandwidth byperforming a single piggyback scheme using both an RS-CID list and anextended sub-header. A value “B” of the extended sub-header type field1405 is defined as another case where the RS requests the allocation ofbandwidth by performing a single piggyback scheme using both an extendedsub-header and a conventional grant management sub-header. A value “C”of the extended sub-header type field 1405 is defined as still anothercase where the RS requests bandwidth allocation based on a multiplepiggyback scheme using both an extended sub-header and order informationof an RS-CID list. A value “D” of the extended sub-header type field1405 is defined as yet another case where the RS requests bandwidthallocation through a multiple piggyback scheme using both an extendedsub-header and a bitmap created from respective RS-CIDs corresponding toan RS-CID list. A value “E” of the extended sub-header type field 1405is defined as yet another case where the RS requests bandwidthallocation based on a multiple piggyback scheme using both an extendedsub-header and other sub-headers for recording CID informationcorresponding to each of several RS-CIDs. These values A, B, C, D and Eare exemplary only, and any other suitable values of the extendedsub-header type field 1405 shown in Tables 4 and 5 (i.e., from 6 to 127in case of UL and from 5 to 127 in case of DL) may be alternativelyused.

FIG. 10 is a view illustrating a single piggyback scheme based on anRS-CID list and an extended sub-header in accordance with an exemplaryembodiment of the present invention.

Referring to FIG. 10, in this single piggyback scheme using the extendedsub-header of this invention, the RS 20 performs a mapping between eachMS-CID of the first MS (MS 100) and its own RS-CID and between eachMS-CID of the second MS (MS 200) and its own RS-CID. For instance, theRS 20 may perform a mapping to connect RS-CID #1, RS-CID #2 and RS-CID#3 to MS-CIDs of the first MS (MS 100), respectively, and also toconnect RS-CID #4, RS-CID #5, RS-CID #6 and RS-CID #7 to MS-CIDs of thesecond MS (MS 200), respectively. This mapping process depends on apredefined CID matching form, and this invention is not limited to theabove CID numbers.

Herein, let's suppose that RS-CID #2 corresponding to MS-CID #105 iscontained in a message transmitted to the BS 30, and that MS-CID #302 ofthe second MS (MS 200) is a bandwidth requesting CID. Then, since eachof the first and second MSs (MS 100 and MS 200) records CID information,bandwidth allocation request information and related field values inMS-CID in order to request the allocation of bandwidth, the RS 20 canascertain whether the MS-CID is for a bandwidth allocation request ornot by checking the above information and field values. Therefore, inthe above mapping process, the RS 20 can ascertain whether there isMS-CID having the contents for a bandwidth allocation request in MS-CIDsof the first and second MSs (MS 100 and MS 200). Namely, the RS 20 canknow that bandwidth requesting CIDs are RS-CID #3, RS-CID #4 and RS-CID#6 in an RS-CID list.

After an RS-CID mapping is completed, the RS 20 arranges RS-CIDsaccording to a given rule and then makes an RS-CID list corresponding tothe arranged RS-CIDs. In this case, the RS 20 makes a generic MAC header100 containing RS-CID #2 and also sets the ESF field of the generic MACheader 100 to “1”. Also, the RS 20 adds an extended sub-header grouplength field 101, an extended sub-header, an extended sub-header type A103, and an extended sub-header body A 105 to the generic MAC header100. Here, the extended sub-header body A 105 has an “RS-CID to PBR(n)”region 107 and a “PBR(16-n)” region 109. The RS-CID to PBR(n) region 107contains rank information about bandwidth requesting RS-CID in theRS-CID list, and the PBR(16-n) region 109 contains bandwidth allocationrequest information required by the bandwidth requesting RS-CID. The RS20 adds this message to the extended sub-header type A 103 and thentransmits it to the BS 30. Here, the size n of the “RS-CID to PBR” fieldmay be obtained through the aforesaid Equation 1.

Meanwhile, the BS 30 receives the message from the RS 20 and checks theESF field to determine whether there is an extended sub-header. If theESF is set to “1”, the BS 30 can know the type of a bandwidth allocationrequest message by checking the extended sub-header type. Namely, incase of the extended sub-header type A, the BS 30 can know which CID inthe RS-CID list requires bandwidth recorded in the PBR(16-n) region 109,and thereby allocates corresponding bandwidth to the RS 20. Then the RS20 allocates the above bandwidth to the MS.

Meanwhile, if the number of CIDs in the RS-CID list is greater than acertain number expressible by the size of the RS-CID to PBR field, theRS 20 cannot perform a proper distinction of CIDs. For instance, if thesize of the RS-CID to PBR field is “5”, the RS 20 can distinguish up tototal 32 CIDs but cannot distinguish CIDs more than 32. Therefore, theRS 20 supports a proper bandwidth allocation request using a datastructure as shown in FIG. 11.

FIG. 11 is a view illustrating a single piggyback scheme using aconventional grant management sub-header and an extended sub-header inaccordance with an exemplary embodiment of the present invention.Namely, FIG. 11 shows a method for requesting the allocation ofbandwidth for CID of the generic MAC header and for other CIDs by usingthe extended sub-header in a single piggyback scheme using aconventional grant management sub-header.

Herein, let's suppose that MS-CIDs of the first MS (MS 100) are mappedto RS-CID #1, RS-CID #2 and RS-CID #3, and MS-CIDs of the second MS (MS200) are mapped to RS-CID #4, RS-CID #5, RS-CID #6 and RS-CID #7.Additionally, let's suppose that RS-CID #6 is bandwidth requesting CID.

Referring to FIG. 11, the RS 20 writes a generic MAC header 110containing RS-CID #2 and also sets the ESF field of the generic MACheader 110 to “1”. Also, the RS 20 adds an extended sub-header grouplength field 111, an extended sub-header, an extended sub-header type B113, and an extended sub-header body B to the generic MAC header 110.Here, the extended sub-header body B has a sub-header for recordingRS-CID to PBR 115 and a conventional grant management sub-header 117.Namely, for a bandwidth allocation request for RS-CID #6, the RS 20 usesthe conventional grant management sub-header 117 as discussed earlier inTable 1. Here, since the conventional grant management sub-header 117contains only bandwidth information required for RS-CID #6, the RS 20transmits RS-CID #6 information, namely the 2-byte sub-header 115containing “RS-CID to PBR”, together with the conventional grantmanagement sub-header 117.

Namely, the RS 20 adds the extended sub-header group length field 111with a fixed size (e.g., 1 byte) to the generic MAC header 110containing RS-CID #2 information, further adds the extended sub-headertype B 113 with 1-byte size, the sub-header 115 containing “RS-CID toPBR” as information about bandwidth requesting RS-CID, and theconventional grant management sub-header 117, and then transmits it tothe BS 30.

Meanwhile, the BS 30 that receives the aforesaid message from the RS 20checks the ESF field of the generic MAC header 110. If the ESF field isset to “1”, the BS 30 can know that the received message is for a singlepiggyback using the extended header. Then the BS 30 detects CIDinformation corresponding to bandwidth requiring RS-CID #6 from thesub-header 115, further detects bandwidth required by RS-CID #6 throughthe conventional grant management sub-header 117, and allocates thedetected bandwidth to the RS 20.

Here, the RS 20 may not need to make a separate RS-CID list when writingbandwidth information about bandwidth requesting RS-CID by using theconventional grant management sub-header 117 and also writing CIDinformation about RS-CID #6 by using the sub-header 115. Additionally,even though using MS-CID itself instead of using RS-CID to which MS-CIDis mapped, the RS 20 may transmit a message for requesting the samebandwidth.

As discussed, in a single piggyback scheme using the extended sub-headerof this invention, the method for requesting the allocation of bandwidthdefines the ESF field of the generic MAC header transmitted to the BS 30and thereby indicates that the current generic MAC header contains abandwidth allocation request message. Also, this method can minimizeCID-related information for a bandwidth allocation request when usingthe extended sub-header, thus minimizing a load caused by messagetransmission for a bandwidth allocation request. Additionally, thismethod can be performed regardless of polling cycle of the BS 30 for acheck of the need for bandwidth, thus minimizing an unnecessary timedelay.

Next, a bandwidth allocation request method based on a multiplepiggyback scheme using an extended sub-header of this invention isdescribed.

FIG. 12 is a view illustrating a multiple piggyback scheme based on anRS-CID list and an extended sub-header in accordance with an exemplaryembodiment of the present invention.

Referring to FIG. 12, the RS 20 performs a mapping so that MS-CID #100,MS-CID #105 and MS-CID #205 of the first MS (MS 100) and MS-CID #252,MS-CID #301, MS-CID #302 and MS-CID #367 of the second MS (MS 200) maybe mapped to its own prearranged RS-CIDs according to a given rule.

After an RS-CID mapping is completed, the RS 20 makes a bandwidthallocation request message, as shown, based on an RS-CID list thatcontains RS-CID #3, RS-CID #4 and RS-CID #6 corresponding to therespective bandwidth requesting MS-CIDs. Specifically, the RS 20extracts RS-CID information from RS-CID #3 and writes it in the CIDfield of the generic MAC header 120. Here, by setting the ESF field ofthe message to “1”, the RS 20 may indicate that the message is torequest the allocation of bandwidth for specific CID by using theextended sub-header. After writing CID information of RS-CID #3 in theCID field of the generic MAC header 120, the RS 20 writes an extendedsub-header group length field 121 added to the generic MAC header 120.Then the RS 20 writes an extended sub-header type C 122 with 1-byte sizefor indicating that the message arranges CID information in order of theRS-CID list, and writes an extended sub-header body C added to theextended sub-header type C 122. Here, the extended sub-header body C mayinclude the first sub-header 125, the second sub-header 128 and thethird sub-header 129.

The first sub-header 125 has a “The number of PBR(n)” region 123 and a“PBR for CID in generic MAC header(16-n)” region 124. The “The number ofPBR(n)” region 123 indicates the total number of PBRs requesting theallocation of bandwidth. Here, the size n may be calculated throughEquation 1 described earlier. The “PBR for CID in generic MACheader(16-n)” region 124 records bandwidth information (e.g., bytes ofbandwidth) required by RS-CID #3.

Each of the second and third sub-headers 128 and 129 has an “RS-CID toPBR(n)” region 126 and a “PBR(16-n)” region 127. The “RS-CID to PBR(n)”region of the second sub-header 128 may record information (i.e., “4”)about the location of RS-CID #4 in the RS-CID list, and the “RS-CID toPBR(n)” region of the third sub-header 129 may record information (i.e.,“6”) about the location of RS-CID #6 in the RS-CID list. Additionally,the “PBR(16-n)” region of the second sub-header 128 records bandwidthallocation request information required by RS-CID #4, and the“PBR(16-n)” region of the third sub-header 129 records bandwidthallocation request information required by RS-CID #6.

Then the RS 20 transmits to the BS 30 the above message including theESF field set to “1”, the generic MAC header 120 containing CID ofRS-CID #3, the extended sub-header group length field 121, the fieldindicating the extended sub-header type C 122, and the extendedsub-header body C added to the extended sub-header type C 122.

Then the BS 30 receives the above message and, by checking the ESF bitof the generic MAC header 120, recognizes the received message to be amultiple piggyback message using the extended sub-header. Additionally,the BS 30 can know the type of a bandwidth request by checking theextended sub-header type. Also, the BS 30 can know how many CIDs requestthe allocation of bandwidth by checking the first sub-header 125, andcan know bandwidth request information through the first, second andthird sub-headers 125, 128 and 129. Then the BS 30 offers acorresponding bandwidth allocation map (e.g., the UL map) to the RS 20.

When receiving the UL map from the BS 30, the RS 20 checks availablebandwidth regions from the UL map and, based thereon, allocatesbandwidth requested by each MS-CID. Then MS recognizes bandwidthallocation for corresponding MS-CID from the RS 20 and may perform datatransmission through the allocated bandwidth.

Here, the length of the extended sub-header body C may be variedaccording to the total number of bandwidth requesting RS-CIDs. Since thelength of the sub-header for a bandwidth allocation request of eachbandwidth requesting RS-CID is 2 bytes, the length of the extendedsub-header body C equals the total number (three) of bandwidthrequesting RS-CIDs multiplied by the length (2 bytes) of the sub-headerfor a bandwidth request. Namely, the length of the extended sub-headerbody C becomes twice a value recorded in a “The number of PBR” fieldcontained in the first sub-header. Additionally, the RS 20 may replace a“The order of CID to PBR” field of the second and third sub-headers 128and 129 with an individual CID index.

As discussed, in case of receiving several bandwidth requesting MS-CIDsfrom at least one MS, the RS 20 creates the RS-CID list based on allMS-CIDs received from the MS, and also fixes the order of respectivebandwidth requesting RS-CIDs. Then the RS 20 records a plan to use theextended sub-header in the generic MAC header for specific RS-CID to betransmitted to the BS 30, sets the extended sub-header type C region,and adds a grant management sub-header for a bandwidth allocationrequest for each CID while using an index value of each CID as thesequence number of each CID. Therefore, the RS 20 can minimize the sizeof a bandwidth allocation request message through a process of adding a2-byte grant management sub-header for each bandwidth requesting CID,thus allowing an integrated management of several bandwidth requestingCIDs.

Meanwhile, the RS 20 may support a quick distinction of bandwidthrequesting RS-CIDs by mapping all CIDs to certain bitmaps. For this, theRS 20 may make a message as shown in FIG. 13.

FIG. 13 is a view illustrating a multiple piggyback scheme based on abitmap and extended sub-header in accordance with an exemplaryembodiment of the present invention. Namely, FIG. 13 shows a process ofmaking a bandwidth allocation request message by mapping all RS-CIDs tobitmaps in the multiple piggyback scheme.

Referring to FIG. 13, the RS 20 creates an RS-CID list by arrangingMS-CIDs of the first and second MSs (MS 100 and MS 200) according to agiven rule. Herein, let's suppose that MS-CID #205 of the first MS (MS100) and MS-CIDs #252 and #302 of the second MS (MS 200) are bandwidthrequesting MS-CIDs.

Then the RS 20 performs a mapping to connect MS-CID #100, MS-CID #105,MS-CID #205, MS-CID #252, MS-CID #301, MS-CID #302 and MS-CID #367 toits own RS-CIDs, respectively, according to a given rule.

In the above mapping process, the RS 20 checks whether there is anyMS-CID having the contents for a bandwidth allocation request in MS-CIDsof the first and second MSs (MS 100 and MS 200). Since each of the firstand second MSs (MS 100 and MS 200) records CID information, bandwidthallocation request information and related field values in MS-CID inorder to request the allocation of bandwidth, the RS 20 can ascertainwhether the MS-CID is for a bandwidth allocation request or not bychecking the above information and field values. Therefore, the RS 20can know that bandwidth requesting CIDs are RS-CID #3, RS-CID #4 andRS-CID #6 in an RS-CID list.

Here, the RS 20 allocates “0” to RS-CID that does not request bandwidthallocation, and allocates “1” to RS-CID that requests bandwidthallocation. Consequently, RS-CID #3, RS-CID #4 and RS-CID #6 that arebandwidth requesting CIDs are assigned “1” and the other RS-CIDs areassigned “0”. Therefore, in case of this example, the RS 20 may create abitmap “0011010” corresponding to the entire RS-CID list.

After the above bitmap creation process is completed, the RS 20 writes ageneric MAC header 130 for specific RS-CID (e.g. RS-CID #2) to betransmitted to the BS 30 and also sets the ESF field of the generic MACheader 130 to “1” to indicate that the bitmap and bandwidth allocationrequest information will use the extended sub-header. Then the RS 20writes a field for indicating an extended sub-header group length field131 added to the generic MAC header 130, and also writes an extendedsub-header type D 132 for indicating that the message is a multiplepiggyback scheme based on the extended sub-header and the bitmap.Additionally, the RS 20 writes an extended sub-header body D added tothe extended sub-header type D 132. Here, the extended sub-header body Drecords bitmap information and bandwidth allocation request informationcorresponding to CID of each bandwidth requesting RS-CID. Namely, theextended sub-header body D includes a sub-header 133 that records“RS-CID BR bitmap”, and also includes conventional grant managementsub-headers 134, 135 and 136 that are added to the sub-header 133 andrecord bandwidth allocation request information for each bandwidthrequesting CID. Namely, the extended sub-header body D includes thefirst conventional grant management sub-header 134 containing bandwidthallocation request information about RS-CID #3, the second conventionalgrant management sub-header 135 containing bandwidth allocation requestinformation about RS-CID #4, and the third conventional grant managementsub-header 136 containing bandwidth allocation request information aboutRS-CID #6.

Therefore, the RS 20 transmits to the BS 30 a message that contains thegeneric MAC header 130, the extended sub-header group length field 131,the extended sub-header type D 132, the sub-header 133 having RS-CID BRbitmap, and the conventional grant management sub-headers 134, 135 and136 having bandwidth allocation request information detected from RS-CID#3, RS-CID #4 and RS-CID #6.

Here, the RS 20 may fix RS-CID BR bitmap to a specific bit or may applyflexibly it. In case where the RS 20 fixes the size of RS-CID BR bitmap,for example, to 2 bytes, the total number of RS-CIDs processed by the RS20 does not exceed 16. Also, in case of 2-byte bitmap, the RS 20 mayassign the aforesaid bitmap “0011010” to former 7 bits and assign “0” tothe other bits. Therefore, the entire bitmap may become“0011010000000000”.

If the ESF field of the generic MAC header 130 received from the RS 20is set to “1”, the BS 30 recognizes the received message to be for amultiple piggyback using the extended sub-header and, by checking theextended sub-header type D 132 region, can know that this message is fora multiple piggyback using bitmap. Then the BS 30 can know which RS-CIDrequires bandwidth allocation by checking bitmap, and also can know theamount of bandwidth actually required by the RS-CID by checking thefirst to third conventional grant management sub-headers 134, 135 and1376 added to the sub-header 133. In this process, the BS 30 makes an ULmap for the allocation of required bandwidth by matching the order ofconventional sub-headers and CID of RS-CID requiring bandwidthallocation, and then sends the UL map to the RS 20.

When receiving the UL map from the BS 30, the RS 20 controls properbandwidth allocation, based on the received UL map, for MS-CID of eachMS that requires bandwidth allocation.

As discussed, in case where the total number of RS-CIDs is expressiblewith a certain bitmap, the bandwidth allocation request method usingbitmap among a multiple piggyback scheme using an extended sub-headermay quickly make and recognize an index for distinction of RS-CIDsrequiring bandwidth allocation, and may write bandwidth allocationrequest information in a conventional grant management sub-header tothereby support the allocation of required bandwidth.

Meanwhile, if the total number of CIDs exceeds a specific bit numberallocated for distinction of CID (e.g., the number expressible by 5bits), for example, if forty CIDs should be processed, or if a bitnumber excessive for the allocation of bitmap is used, the RS 20 maymake a message as shown in FIG. 14.

FIG. 14 is a view illustrating a multiple piggyback scheme based onplural conventional grant management sub-headers and an extendedsub-header in accordance with an exemplary embodiment of the presentinvention. Namely, FIG. 14 shows a process of making a bandwidthallocation request message regardless of the total number of RS-CIDs orlist in the multiple piggyback scheme.

Herein, as supposed in FIG. 10, let's suppose that MS-CIDs of the firstMS (MS 100) are mapped to RS-CID #1, RS-CID #2 and RS-CID #3, andMS-CIDs of the second MS (MS 200) are mapped to RS-CID #4, RS-CID #5,RS-CID #6 and RS-CID #7. Additionally, let's suppose that RS-CID #6 isbandwidth requesting CID.

Referring to FIG. 14, the RS 20 writes a generic MAC header 140 based onCID contained in bandwidth requesting RS-CID #3 and also sets the ESFfield of the generic MAC header 140 to “1”. Then the RS 20 writes anextended sub-header group length field 141 added to the generic MACheader 140. Thereafter, the RS 20 writes an extended sub-header type E142 for indicating that the message is a type using several conventionalgrant management sub-headers among a multiple piggyback scheme based onthe extended sub-header. Additionally, the RS 20 defines an extendedsub-header body E region that is added to the extended sub-header type E142 and contains CID information about bandwidth requesting RS-CIDs andbandwidth allocation request information.

Here, the extended sub-header body E region may include the firstsub-header 145 proposed by this invention, and two conventional grantmanagement sub-headers, namely the second and third conventional grantmanagement sub-headers 147 and 149. The first sub-header 145 has a “Thenumber of PBR(n)” region 143 and a “PBR for CID in generic MACheader(16-n)” region 144. The “The number of PBR(n)” region 143indicates the total number of PBRs requesting the allocation ofbandwidth. Here, the size n may be calculated through Equation 1described earlier. The “PBR for CID in generic MAC header(16-n)” region145 records bandwidth allocation request information (e.g., bytes ofbandwidth) required by RS-CID #3.

Meanwhile, the RS 20 records bandwidth allocation request informationcorresponding to RS-CID #4 and RS-CID #6 in the second and thirdconventional grant management sub-headers 147 and 149, respectively. Inthis example, since the second and third conventional grant managementsub-headers 147 and 149 record only required bandwidth allocationrequest information, other second and third sub-headers 146 and 148 withdistinguishable CID are added to the second and third conventional grantmanagement sub-headers 147 and 149, respectively.

Namely, after setting the ESF field of the generic MAC header 140 to“1”, the RS 20 makes a message that contains the generic MAC header 140,the extended sub-header group length filed 141, the extended sub-headertype E region 142 and the extended sub-header body E, and then transmitsit to the BS 30.

The BS 30 receives from the RS 20 the message in which the ESF field ofthe generic MAC header 140 is “1”, and checks the extended sub-headertype. If the extended sub-header type is “E”, the BS 30 recognizes thereceived message to be for a multiple piggyback using severalconventional grant management sub-headers. Therefore, the BS 30ascertains the total number of PBRs by checking the first sub-header 145and in this process, by checking the “PBR for CID in generic MACheader(16-n)” region 144, can obtain bandwidth allocation requestinformation required by CID contained in the generic MAC header 140.Thereafter, the BS 30 checks the second sub-header 146, the secondconventional grant management sub-header 147, the third sub-header 148and the third conventional grant management sub-header 149, therebyobtains total CID information and total bandwidth allocation requestinformation required by the RS 20, and then transmits the UL map for theallocation of required bandwidth to the RS 20.

When receiving the UL map from the BS 30, the RS 20 creates an UL-MAPfor allocating bandwidth corresponding to MS-CID of each MS and thensends it to each MS. The MS receives the UL-MAP from the RS 20 and,based on allocated bandwidth, transmits data to the BS 30.

As discussed, in several types of multiple piggyback scheme using anextended sub-header, the RS 20 not only writes a generic MAC header anda grant management sub-header corresponding to bandwidth requiringRS-CID, but also includes a sub-header that records CID information anda conventional grant management sub-header that contains bandwidthallocation request information. Therefore, the RS 20 does not need anyseparate RS-CID list and can make a bandwidth allocation request messageby using MS-CID received from the MS as it is.

Described hereinbefore are methods for performing a single piggyback ora multiple piggyback by using a grant management sub-header or by usinga grant management sub-header based on an extended sub-header amongmethods for requesting the allocation of bandwidth according toembodiments of this invention. Now, methods for allocating bandwidth atthe RS and at the BS are discussed with reference to the drawings.

FIGS. 15 and 16 are flow diagrams illustrating a method for requestingthe allocation of bandwidth at a relay station in accordance with anexemplary embodiment of the present invention.

Referring to FIGS. 15 and 16, in step 101, the RS establishes RS-CIDsmapped to MS-CIDs of the MSs that belong to its coverage, arranges CIDof the MSs being in communication therewith, and the makes an RS-CIDlist based on the established RS-CIDs.

Next, in step 103, the RS determines whether there is any MS-CIDrequesting the allocation of bandwidth in MS-CIDs. The MS inserts CIDinformation and necessary bandwidth allocation request information in anMS-CID message transmitted to the RS. So, if a specific type is set inan MAC signaling header for bandwidth requesting CID, the RS candistinguish CID requiring bandwidth allocation by checking it.

If there is no bandwidth allocation request among MS-CIDs in the step103, the RS sets both an LSB bit and an e-PBR bit in a type field of ageneric MAC header to “0” and then creates a message free of bandwidthallocation in step 105.

Meanwhile, if there need to be a bandwidth allocation request in thestep 103, the RS determines whether to use an extended sub-header instep 107. If a message will be made based on the extended sub-header,the RS sets the ESF field to “1” in step 109 and then determines whetherbandwidth requesting MS-CID or RS-CID mapped to MS-CID is more than onein step 111.

If bandwidth requesting CID is a single in the step 111, the RS performsa single piggyback by setting the extended sub-header type to A or B instep 113.

When performing a single piggyback in the step 113, the RS uses theorder of CIDs set to RS-CID as identifiers of RS-CID. In case wherebandwidth allocation request information about RS-CID is recordedadjoining the identifier of RS-CID, the RS may set the extendedsub-header type to “A”. Alternatively, in case where CID informationcorresponding to bandwidth requesting RS-CID is recorded in a sub-headerand also related bandwidth allocation request information is recorded ina conventional grant management sub-header added to the abovesub-header, the RS sets the extended sub-header type to “B”.

Meanwhile, if bandwidth requesting CID is more than one in the step 111,the RS sets the extended sub-header type to one of C, D and E, andperforms a multiple piggyback in step 115.

The extended sub-header type C is set in case where the RS requestsbandwidth allocation based on a multiple piggyback scheme using both anextended sub-header and order information of an RS-CID list. Theextended sub-header type D is set in case where the RS requestsbandwidth allocation through a multiple piggyback scheme using both theextended sub-header and a bitmap created from respective RS-CIDscorresponding to an RS-CID list. The extended sub-header type E is setin case where the RS requests bandwidth allocation based on a multiplepiggyback scheme using both an extended sub-header and other sub-headersfor recording CID information corresponding to each of several RS-CIDs.

On the other hand, if no extended sub-header is used in the step 107,the RS determines whether bandwidth requesting CID is more than one instep 117.

If bandwidth requesting CID is more than one in the step 117, the RSsets the LSB bit and the e-PBR bit of the generic MAC header to “0” and“1”, respectively, in step 119, and then performs a multiple piggybackbased on a grant management sub-header in step 121.

A multiple piggyback scheme based on the grant management sub-headerincludes a type of using an RS-CID list, a type of using a bitmap, and atype of using several conventional grant management sub-headers.

A multiple piggyback scheme using the RS-CID list is to extract theorder of bandwidth requesting RS-CIDs from the RS-CID list of arrangedRS-CIDs corresponding to respective MS-CIDs and then to write togetherthis order information and bandwidth allocation request information ofCID. Here, the RS writes information about the total number of bandwidthrequesting CIDs, and bandwidth allocation information for each CID maybe recorded using the conventional grant management sub-header.

A multiple piggyback scheme using the bitmap is to make a map of bitvalues by assigning bandwidth requesting RS-CIDs to “1” andnon-bandwidth requesting RS-CIDs to “0” in an RS-CID list and then todistinguish bandwidth requesting CIDs through such bit values. Inproportion to the number of CIDs assigned “1”, the RS adds conventionalgrant management sub-headers that record bandwidth allocation requestinformation about such CIDs assigned “1” in the bitmap.

A multiple piggyback scheme using the several conventional grantmanagement sub-headers is to extract CIDs from respective bandwidthrequesting RS-CIDs, to add sub-headers for recording such CIDs, toarrange a conventional grant management sub-header for recordingbandwidth allocation request information about each CID to adjoin eachsub-header, and thereby to make a message.

If bandwidth requesting CID is a single in the step 117, the RSdetermines whether CID contained in a generic MAC header requests theallocation of bandwidth in step 123.

If CID contained in the generic MAC header is bandwidth requesting CIDin the step 123, the RS sets the LSB bit and the e-PBR bit of thegeneric MAC header to “1” and “0”, respectively, in step 125, and thenperforms a piggyback for CID contained in the generic MAC header in step127.

Meanwhile, if bandwidth requesting CID is not CID contained in thegeneric MAC header but other CID in the step 123, the RS sets both theLSB bit and the e-PBR bit of the generic MAC header to “1” in step 129,and then performs a single piggyback based on a grant managementsub-header in step 131.

Here, a single piggyback scheme based on the grant management sub-headerincludes a single piggyback scheme based on an RS-CID list and a singlepiggyback scheme using a conventional grant management sub-header.

A single piggyback scheme based on the RS-CID list is to use, as anRS-CID identifier, an index value corresponding to the order ofbandwidth requesting RS-CIDs in the RS-CID list, and then to writetogether this RS-CID identifier and bandwidth allocation requestinformation of the RS-CID identifier. This message adds 2-bytesub-header.

A single piggyback scheme using the conventional grant managementsub-header is to assign 2-byte sub-header for CID information ofbandwidth requesting RS-CID, and to record bandwidth allocation requestinformation corresponding to CID information in the 2-byte sizedconventional grant management sub-header added to the above sub-header.

As discussed heretofore, the method for requesting the allocation ofbandwidth according to embodiments of this invention may support variousschemes, depending on the number of bandwidth requesting CIDs, the useor not of an extended sub-header, and the use or not of a grantmanagement sub-header. Additionally, in each scheme, by allowing anintegrated management of a conventional process of having to transmit a6-byte generic MAC header for each CID in order to request bandwidthallocation, the method of this invention may reduce the size of amessage, also reduce the number of message transmission and reception,and thereby decrease the network load.

FIG. 17 is a flow diagram illustrating a method for allocating bandwidthat a base station in accordance with an exemplary embodiment of thepresent invention.

Referring to FIG. 17, in step 201, the BS receives a generic MAC headerfrom the RS. Then, in step 203, the BS determines whether the extendedsub-header field ESF of the generic MAC header is “1”.

If the ESF is “1” in the step 203, the BS ascertains that the receivedgeneric MAC header has the extended sub-header in step 205. Then, instep 207, the BS checks a grant management sub-header depending on theextended sub-header type. Namely, in the step 207, the BS ascertains thetype A, B, C, D or E of the extended sub-header added to the receivedgeneric MAC header and then checks each sub-header differently definedaccording to the type.

Then, in step 209, the BS obtains information about bandwidth requestingCID and bandwidth allocation request information. Based thereon, in step211, the BS makes a bandwidth allocation map and sends it to the RS.

Meanwhile, if the ESF region is not “1” in the step 203, the BSdetermines whether the e-PBR region is “0” in step 213.

If the e-PBR region is “0” in the step 213, the BS further determineswhether the LSB bit of the type field is “1” in step 215. If the LSB bitis not “1” in the step 215, the BS terminates a process without anyallocation of bandwidth. If the LSB bit is “1” in the step 215, the BSascertains that the received message is a piggyback for CID contained inthe generic MAC header in step 217, and then performs the aforesaidsteps 209 and 211.

On the other hand, if the e-PBR region is not “0” in the step 213, theBS further determines whether the LSB bit is “0” in step 219. If the LSBbit is “0” in the step 219, the BS ascertains that the received messageis a multiple piggyback based on a grant management sub-header in step221. Then the BS performs the aforesaid steps 209 and 211. Here, in casewhere the received message is a multiple piggyback based on a grantmanagement sub-header, the BS may find bandwidth requesting CIDs andbandwidth allocation request information by checking sub-headers addedto the generic MAC header.

If the LSB bit is not “0” in the step 219, the BS ascertains that thereceived message is a single piggyback based on a grant managementsub-header in step 223, and then performs the aforesaid steps 209 and211.

While this invention has been particularly shown and described withreference to an exemplary embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

1. A method for requesting the allocation of bandwidth for at least onemobile station (MS) using several connection identifications (CIDs) in amulti-hop relay environment, the method comprising steps of: at a relaystation (RS), ascertaining the CIDs of the MS that belongs to the RS; atthe RS, detecting bandwidth requesting CID that requires the allocationof bandwidth, among the CIDs; at the RS, creating a field that containsa region for recording CID-related information of the bandwidthrequesting CID and a region for recording bandwidth request informationof the bandwidth requesting CID; and at the RS, adding the created fieldto a media access control (MAC) header that corresponds to CID of apacket transmitted to a base station (BS) among the CIDs.
 2. The methodof claim 1, wherein if the bandwidth requesting CID is a single in thedetecting step, the creating step is to record the order of thebandwidth requesting CID arranged in a list of the CIDs as theCID-related information.
 3. The method of claim 1, wherein if thebandwidth requesting CID is a single in the detecting step, the creatingstep is to record the bandwidth requesting CID as the CID-relatedinformation.
 4. The method of claim 1, wherein if the bandwidthrequesting CID is more than one in the detecting step, the creating stepincludes: creating a first field by recording the total number of thebandwidth requesting CIDs in the CID-related information and also byrecording bandwidth request information corresponding to CID containedin the MAC header; and creating a second field for each bandwidthrequesting CID by recording the order of the bandwidth requesting CID,excepting the CID contained in the MAC header, arranged in a list of theCIDs as a CID-related information region and also by recording thebandwidth request information of the CID in the CID-related informationregion.
 5. The method of claim 1, wherein if the bandwidth requestingCID is more than one in the detecting step, the creating step includes:creating bitmap information for distinguishing the bandwidth requestingCID from non-bandwidth requesting CID in a list of the CIDs and thenrecording the bitmap information as the CID-related information; andrecording the bandwidth request information of each bandwidth requestingCID.
 6. The method of claim 1, wherein if the bandwidth requesting CIDis more than one in the detecting step, the creating step includes:creating a first field by recording the total number of the bandwidthrequesting CIDs as the CID-related information and also by recordingbandwidth request information for CID contained in the MAC header; andcreating a second field for each bandwidth requesting CID by recordingthe CID corresponding to the bandwidth requesting CID and also byrecording the bandwidth request information of the CID.
 7. The method ofclaim 1, wherein if the bandwidth requesting CID is a single and uses anextended sub-header in the detecting step, the creating step includes:recording an extended sub-header group length field and an extendedsub-header type field; and recording an extended sub-header body fieldcontaining the CID-related information and the bandwidth informationaccording to the type of the extended sub-header type field.
 8. Themethod of claim 7, wherein if the extended sub-header type is a firstvalue, the creating step is to write the extended sub-header body fieldby recording the order of the bandwidth requesting CID arranged in alist of the CIDs in the CID-related information and also by recordingthe bandwidth request information of the CID.
 9. The method of claim 7,wherein if the extended sub-header type is a second value, the creatingstep is to write the extended sub-header body field by recording thebandwidth requesting CID as the CID-related information and also byrecording the bandwidth request information of the CID.
 10. The methodof claim 7, wherein if the extended sub-header type is a third value,the creating step is to write the extended sub-header body field,including: creating a first field by recording the total number of thebandwidth requesting CIDs in the CID-related information and also byrecording bandwidth request information corresponding to CID containedin the MAC header; and creating a second field for each bandwidthrequesting CID by recording the order of the bandwidth requesting CID,excepting the CID contained in the MAC header, arranged in a list of theCIDs as a CID-related information region and also by recording thebandwidth request information of the CID in the CID-related informationregion.
 11. The method of claim 7, wherein if the extended sub-headertype is a fourth value, the creating step is to write the extendedsub-header body field, including: creating bitmap information fordistinguishing the bandwidth requesting CID from non-bandwidthrequesting CID in a list of the CIDs and then recording the bitmapinformation as the CID-related information; and recording the bandwidthrequest information of each bandwidth requesting CID.
 12. The method ofclaim 7, wherein if the extended sub-header type is a fifth value, thecreating step is to write the extended sub-header body field, including:creating a first field by recording the total number of the bandwidthrequesting CIDs as the CID-related information and also by recordingbandwidth request information for CID contained in the MAC header; andcreating a second field for each bandwidth requesting CID by recordingthe CID corresponding to the bandwidth requesting CID and also byrecording the bandwidth request information of the CID.
 13. A system forrequesting the allocation of bandwidth for at least one mobile station(MS) using several connection identifications (CIDs) in a multi-hoprelay environment, the system comprising: a relay station (RS)configured to ascertain the CIDs of the MS, to detect bandwidthrequesting CID that requires the allocation of bandwidth among the CIDs,to create a field that contains a region for recording CID-relatedinformation of the bandwidth requesting CID and a region for recordingbandwidth request information of the bandwidth requesting CID, and toadd the created field to a media access control (MAC) header thatcorresponds to CID of a packet transmitted to a base station (BS) amongthe CIDs.
 14. The system of claim 13, wherein the RS is furtherconfigured to, if the bandwidth requesting CID is a single, record theorder of the bandwidth requesting CID arranged in a list of the CIDs asthe CID-related information.
 15. The system of claim 13, wherein the RSis further configured to, if the bandwidth requesting CID is a single,record the bandwidth requesting CID as the CID-related information. 16.The system of claim 13, wherein the RS is further configured to, if thebandwidth requesting CID is more than one, create a first field byrecording the total number of the bandwidth requesting CIDs in theCID-related information and also by recording bandwidth requestinformation corresponding to CID contained in the MAC header, and tocreate a second field for each bandwidth requesting CID by recording theorder of the bandwidth requesting CID, excepting the CID contained inthe MAC header, arranged in a list of the CIDs as a CID-relatedinformation region and also by recording the bandwidth requestinformation of the CID in the CID-related information region.
 17. Thesystem of claim 13, wherein the RS is further configured to, if thebandwidth requesting CID is more than one, create bitmap information fordistinguishing the bandwidth requesting CID from non-bandwidthrequesting CID in a list of the CIDs, to record the bitmap informationas the CID-related information, and to record the bandwidth requestinformation of each bandwidth requesting CID.
 18. The system of claim13, wherein the RS is further configured to, if the bandwidth requestingCID is more than one, create a first field by recording the total numberof the bandwidth requesting CIDs as the CID-related information and alsoby recording bandwidth request information for CID contained in the MACheader, and to create a second field for each bandwidth requesting CIDby recording the CID corresponding to the bandwidth requesting CID andalso by recording the bandwidth request information of the CID.
 19. Thesystem of claim 13, wherein the RS is further configured to, if thebandwidth requesting CID is a single and uses an extended sub-header,record an extended sub-header group length field and an extendedsub-header type field, and to record an extended sub-header body fieldcontaining the CID-related information and the bandwidth informationaccording to the type of the extended sub-header type field.
 20. Thesystem of claim 19, wherein the RS is further configured to, if theextended sub-header type is a first value, write the extended sub-headerbody field by recording the order of the bandwidth requesting CIDarranged in a list of the CIDs in the CID-related information and alsoby recording the bandwidth request information of the CID.
 21. Thesystem of claim 19, wherein the RS is further configured to, if theextended sub-header type is a second value, write the extendedsub-header body field by recording the bandwidth requesting CID as theCID-related information and also by recording the bandwidth requestinformation of the CID.
 22. The system of claim 19, wherein the RS isfurther configured to, if the extended sub-header type is a third value,write the extended sub-header body field, including to create a firstfield by recording the total number of the bandwidth requesting CIDs inthe CID-related information and also by recording bandwidth requestinformation corresponding to CID contained in the MAC header, and tocreate a second field for each bandwidth requesting CID by recording theorder of the bandwidth requesting CID, excepting the CID contained inthe MAC header, arranged in a list of the CIDs as a CID-relatedinformation region and also by recording the bandwidth requestinformation of the CID in the CID-related information region.
 23. Thesystem of claim 19, wherein the RS is further configured to, if theextended sub-header type is a fourth value, write the extendedsub-header body field, including to create bitmap information fordistinguishing the bandwidth requesting CID from non-bandwidthrequesting CID in a list of the CIDs and then recording the bitmapinformation as the CID-related information, and to record the bandwidthrequest information of each bandwidth requesting CID.
 24. The system ofclaim 19, wherein the RS is further configured to, if the extendedsub-header type is a fifth value, write the extended sub-header bodyfield, including to create a first field by recording the total numberof the bandwidth requesting CIDs as the CID-related information and alsoby recording bandwidth request information for CID contained in the MACheader, and to create a second field for each bandwidth requesting CIDby recording the CID corresponding to the bandwidth requesting CID andalso by recording the bandwidth request information of the CID.